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Nuclear Theory·nucl-th

Wednesday·October 17, 2018

12 papers—6 primary·6 cross-listed

All12Primary6Cross-lists6
  1. 07

    [Submitted on 15 Oct 2018] (cross-list from hep-ph)

    Strong- vs. weak-coupling pictures of jet quenching: a dry run using QED

    Peter Arnold🇺🇸 · Shahin Iqbal🇵🇰 · Tanner Rase🇺🇸

    High-energy partons () traveling through a quark-gluon plasma lose energy by splitting via bremsstrahlung and pair production. Regardless of whether or not the quark-gluon plasma itself is strongly coupled, an important question lying at the heart of philosophically different approaches to energy loss is whether the high-energy partons of an in-medium shower can be thought of as a collection of individual particles, or whether their coupling to each other is also so strong that a description as high-energy `particles' is inappropriate. We discuss some possible theorists' tests of this question for simple situations (e.g. an infinite, non-expanding plasma) using thought experiments and first-principles quantum field theory calculations (with some simplifying approximations). The physics of in-medium showers is substantially affected by the Landau-Pomeranchuk-Midgal (LPM) effect, and our proposed tests require use of what might be called `next-to-leading order' LPM results, which account for quantum interference between consecutive splittings. The complete set of such results is not yet available for QCD but is already available for the theory of large- QED. We therefore use large- QED as an example, presenting numerical results as a function of , where is the strength of the coupling at the relevant high-energy scale characterizing splittings of the high-energy particles.

    Comments:
    31 pages + appendices for 48 pages total, 21 figures. [Difference from version 2: Main change was to eliminate some summary formulas of NLO rates in section III.B, made unnecessary by a clear summary of formulas having been added to ref. [13].]
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1810.06578 [pdf]
    JHEP(2019)·20 citations
  2. 08

    [Submitted on 15 Oct 2018] (cross-list from hep-ph)

    Virtual axion-like particle complement to Euler-Heisenberg-Schwinger action

    Stefan Evans🇺🇸 · Johann Rafelski🇺🇸

    We modify action in an external electromagnetic field to include effects of virtual axion-like particle (ALP) excitations. A measurable addition to QED-Euler-Heisenberg-Schwinger (EHS) action is obtained and incorporated into experimental constraints placed on ALP mass and coupling to two photons. The regime of these constraints in which the ALP vacuum effect surpasses the EHS effect is characterized. We show that probing of the virtual vacuum effect offers an alternative method in search for physics related to ALPs.

    Comments:
    5 pages, 2 figures
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1810.06717 [pdf]
    PLB(2019)·16 citations
  3. 09

    [Submitted on 16 Oct 2018] (cross-list from hep-ph)

    Systematic studies of charmonium-, bottomonium-, and -like tetraquark states

    Jing Wu🇨🇳 · Xiang Liu🇨🇳 · Yan-Rui Liu🇨🇳 · Shi-Lin Zhu🇨🇳

    We study the mass splittings of (, ) tetraquark states with chromomagnetic interactions between their quark components. Assuming that is the lowest tetraquark, we estimate the masses of the other tetraquark states. From the obtained masses and defined measure reflecting effective quark interactions, we find the following assignments for several exotic states: (1) both and the newly observed seem to be tetraquarks; (2) is probably a tetraquark; (3) , , and are unlikely compact tetraquarks; (4) is unlikely a compact tetraquark, but seems the hidden-charm correspondence of with ; and (5) can be a tetraquark candidate but the quantum numbers cannot be assigned at present. We hope further studies may check the predictions and assignments given here.

    Comments:
    23 pages, 5 figures, 13 tables. Version will appear in Phys. Rev. D
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1810.06886 [pdf]
    PRD(2019)·60 citations
  4. 10

    [Submitted on 16 Oct 2018] (cross-list from hep-ph)

    Remarks on the Heavy-Quark Flavour Symmetry for doubly heavy hadronic molecules

    V. Baru🇩🇪 · E. Epelbaum🇩🇪 · J. Gegelia🇩🇪 · C. Hanhart🇩🇪 · U.-G. Meißner🇩🇪 · A. V. Nefediev🇷🇺

    The possibility for a common effective field theory for hadronic molecules with different heavy-quark flavours is examined critically. It is argued that such a theory does not allow one to draw definite conclusions for doubly heavy molecules. In particular, it does not allow one to relate binding energies for the molecules in the c-quark and b-quark sectors with controlled uncertainties. Therefore, while this kind of reasoning does not preclude from employing heavy-quark spin symmetry for charmonium- and bottomonium-like states separately within a well established effective field theory framework, relations between different heavy-quark sectors can only be obtained using phenomenological approaches with uncontrolled uncertainties.

    Comments:
    7 pages, extended discussions, added references, version to appear in Eur. Phys. J. C
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1810.06921 [pdf]
    EPJC(2019)·23 citations
  5. 11

    [Submitted on 16 Oct 2018] (cross-list from hep-ph)

    Bethe-Salpeter-Motivated Modelling of Pseudo-Goldstone Pseudoscalar Mesons

    Wolfgang Lucha🇦🇹

    We apply a description of bound states of fermion and antifermion by means of our approximation to the Bethe-Salpeter formalism that retains part of the information on relativistic effects provided by the full fermion propagator to the lightest pseudoscalar mesons. Therein, the pseudo-Goldstone nature of the latter quark-antiquark bound states is taken into account by appropriately formulated effective interactions. Scrutinizing the predictions of this bound-state approach for meson masses, decay constants and in-meson condensates by relying on a generalized Gell-Mann-Oakes-Renner relation shows that the light-quark-mass values required for agreement are all in the right ballpark.

    Comments:
    8 pages, 3 figures, contributed to "XIII Quark Confinement and the Hadron Spectrum - Confinement2018" (31 July - 6 August 2018, Maynooth University, Ireland)
    Subjects:
    High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    1810.06958 [pdf]
    PoS(2018)·0 citations
  6. 12

    [Submitted on 16 Oct 2018] (cross-list from nucl-ex)

    Collective Effects in Nuclear Collisions: Experimental Overview

    You Zhou🇩🇰

    These conferences proceedings summarize the experimental findings of collective effects in nuclear collisions, as presented at the Quark Matter 2018 conference.

    Comments:
    Final version of proceedings for an invited overview talk in XXVIIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2018), Venezia, Italy
    Subjects:
    Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
    arXiv:
    1810.06978 [pdf]
    NPA(2019)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE